class _const:
    class ConstError(TypeError): pass
    class ConstCaseError(ConstError): pass
    def __setattr__(self, name, value):
        if self.__dict__.get(name):
            raise self.ConstError("Can't change const.%s" % name)
        if not name.isupper():
            raise self.ConstCaseError('const name "%s" is not all uppercase' % name)
        self.__dict__[name] = value


import sys

sys.modules[__name__]=_const()
